Analyses and forecast of water resources in an ultra-centenarian spring discharge series from Serino (Southern Italy)

SummaryStatistical and specific correlation data analyses have been carried out on an ultra-centenarian hydrological series to establish the relationship between spring discharge and rainfall. Analyses focused on the Serino springs, the main spring area of the karst aquifer in the Terminio massif (Southern Italy), which supplies the Naples area with a discharge of approximately 1–3.5 m3/s. Due to the Mediterranean climate, which causes a rapid increase in evapotranspiration and a decrease in rainfall towards spring–summer, spring discharge amplifies the effect of poor rainfall, especially during drought, and appears to be a highly sensitive climatic parameter. A specific index (cumulative effective rainfall index, Δi) has been introduced to evaluate aquifer recharge. Its high correlation with spring discharge made it possible to establish a cumulative effective rainfall threshold of 450 mm for aquifer response. Below this value, aquifer discharge exceeds recharge and an ‘anomalous’ spring hydrograph is observed, which is precisely what occurred during the droughts of 1949 and 2002. Cross-correlation between moving cumulative rainfall and daily spring discharge have shown a wide range of the water pore pressure transfer time inside the Serino karst aquifer. Effects of changes in hydrological extremes are investigated, and frequency of droughts and spring discharge forecasting are also discussed.